how to compute this probability?

I have taken this problem from the paper of MASTER OF COMMERCE Examination of university in India with little modifications.
If a machine is correctly set up it will produce 90% acceptable items. If it is incorrectly set up it will produce 40% acceptable items. Past 5 years experience shows 80% of the setups are correctly done. If after a certain setup
1) machine produces 3 acceptable items and 1 non-acceptable( defective ) item as the first 4 pieces, find the probability that machine is correctly setup.
2)machine produces 3 acceptable items as the first 3 pieces,find the probability that the machine is correctly setup.

Answer: I have calculated the answer for 1)0.39724128 and for 2)0.99310345

I don't know what are the correct answers.So verification of these answers is needed.

Re: how to compute this probability?

Originally Posted by Vinod

I have taken this problem from the paper of MASTER OF COMMERCE Examination of university in India with little modifications.
If a machine is correctly set up it will produce 90% acceptable items. If it is incorrectly set up it will produce 40% acceptable items. Past 5 years experience shows 80% of the setups are correctly done. If after a certain setup
1) machine produces 3 acceptable items and 1 non-acceptable( defective ) item as the first 4 pieces, find the probability that machine is correctly setup.
2)machine produces 3 acceptable items as the first 3 pieces,find the probability that the machine is correctly setup.

Answer: I have calculated the answer for 1)0.39724128 and for 2)0.99310345

I don't know what are the correct answers.So verification of these answers is needed.

By my calculations neither is right.

Tell us how you approached this and then we might be able to see where you went wrong.